ATLANTA -- Thousands of Marines and their families went to serve their country at North Carolina's Camp Lejeune.

Instead, many wound up fighting it, blaming the government for failing to protect them from an enemy that invaded their lives in a most intimate way: through the water that quenched their thirst, cooked their food and filled their bathtubs every day.

The gruff ex-drill instructor is angry leukemia claimed his daughter, Janey. Parents were guilt-ridden that perhaps their own actions had ruined their daughters' health. An aging major still mourns the wife who shared his torment over their baby's fatal birth defects. A former Navy doctor's career was demolished by his rare cancer.

Each used the water that poured from kitchen faucets and bathroom showers at Camp Lejeune, an environmental tragedy realized a generation ago that is drawing new scrutiny from members of Congress outraged over the government's treatment of sick veterans at Walter Reed Army Medical Center and elsewhere.

U.S. health officials here in Atlanta hope to finish a long-awaited study by year's end to examine whether the water tainted with solvents affected the health of children. It will influence the Pentagon's response to at least 850 pending legal claims by people who lived at the Marine base, officials said. The former residents, who together seek nearly $4 billion, believe their families were afflicted by water containing industrial solvents before the Marines shut off the bad wells in the mid-1980s.

At least 120,000 people lived in family housing that may have been affected over three decades, plus uncounted civilian workers and Marines in barracks, Marine Corps figures indicate. Defense officials recently told U.S. health investigators that between 1975 and 1985 alone, nearly 200,000 Marines were stationed at Camp Lejeune.

About 56,000 Marines, family members and civilians now live or work at Camp Lejeune, the sprawling training and deployment base on the Atlantic seaboard. Its water meets current federal standards.

Health officials and lawmakers complain that the Defense Department has delayed disclosure of important documents during investigations into the health impact of water contaminated by a dry cleaner adjacent to Camp Lejeune and by the base's past industrial activities.

"We wouldn't be investigating this disgraceful situation if (the Department of Defense) had put half as much effort into cleaning up the water as it has into stonewalling those who drank it," said Rep. John Dingell, D-Mich., chairman of the House Energy and Commerce Committee. A subcommittee expects to conduct an oversight hearing Tuesday, the first in a broader review by Democrats investigating the Pentagon's environmental record.

The scrutiny comes as federal regulators consider whether to tighten restrictions on solvents known as TCE, trichloroethylene, and PCE, tetrachloroethylene, common contaminants at military and private industrial sites. The chemicals were highlighted in a 1998 movie starring John Travolta, "A Civil Action," about a lawsuit against corporate polluters in Woburn, Mass.

Marine Corps officials said Camp Lejeune followed environmental rules in effect at the time.

"The health and safety of our Marines and their dependents is of primary concern to the Marine Corps," the service said in a statement. "Base officials provided drinking water consistent with industry practices at the time."

Rep. Barton Stupak, D-Mich., who will preside over the upcoming congressional hearings, complained that the Defense Department considers environmental cleanups to be a low priority. "That has to change," he said.

Government health experts now believe the truth at Camp Lejeune is worse than anyone knew: Its water was contaminated as far back as 1957, and until 1987.

The newly recognized endpoint -- nearly two years after the Marines said they closed all the tainted wells -- is identified in a new federal water study scheduled for release this month. It is part of the continuing government study by the Agency for Toxic Substances and Disease Registry into whether Camp Lejeune's water led to leukemia and birth defects in children.

Camp Lejeune's population is believed the largest ever exposed to the solvents at such high levels. The Environmental Protection Agency is overseeing cleanups at more than 150 military installations polluted by the same chemicals. Drinking water usually was unaffected, but underground contamination migrated to surrounding neighborhoods and wells at some sites.

From Cape Cod to the Hawaiian islands, the Defense Department has been forced to provide bottled water, treat ground water and well water and switch residents to municipal water systems. But those incidents have rarely led to litigation or claims like those against Camp Lejeune.

--At the former McClellan Air Force Base in northern California, pollution forced officials to close neighborhood wells, including one that served 23,000 people, after TCE and PCE were found migrating from the base in 1979. Residents now are connected to municipal water systems.

--On Cape Cod, the Massachusetts Military Reservation polluted the main water source for thousands of local residents with hazardous solvents, rocket fuel and other toxins over many years. Officials closed numerous wells and connected residents to municipal water. The Air Force built water treatment systems and the cleanup continues.

At Camp Lejeune, the Marine Corps said in a written statement it gave U.S. health investigators "full access" to its records, including "vast and varied" documents, e-mails, maps, contracts and technical information. However, military lawyers acknowledged they are blocking plans for health officials to disclose some records publicly, citing privacy, legal and security concerns.

"We have always sought to provide a timely response to (health investigators') requests for documents within our control," the Marine Corps said.

Health officials repeatedly have complained about slow Defense responses to their information requests, correspondence shows. Military officials initially opposed a full study of child illnesses and balked for three years at paying for it, according to documents reviewed by The Associated Press.

A criminal investigation by the Environmental Protection Agency and Justice Department in 2005 at Camp Lejeune noted that federal rules limiting TCE and PCE in drinking water were not in effect until 1989 and 1992 -- years after the exposure. The probe found no legal violation or conspiracy to conceal information.

Families are convinced drinking and bathing in the water made them sick, although proof is elusive. They are angry the wells ran for four years after the first sign of contamination in 1980 and 1981, and that the government hasn't notified others who were likely exposed at Camp Lejeune.

Among revelations drawing new scrutiny from Washington: On four occasions to ease a temporary water shortage in 1985 the Marines quietly reopened one well at night even after they had shut it down because of contamination.

Two former Marines, retired Master Sgt. Jerry Ensminger and retired Maj. Tom Townsend, have directed their grief into an encyclopedic collection of historical documents, hydrology data, e-mails and other military files they obtained mostly under the Freedom of Information Act. Townsend's stack of papers reaches 20 feet.

Townsend's infant son, Christopher, suffered a fatal heart malformation and other birth defects. By the time his wife of 52 years died of liver cirrhosis last year, Townsend was sure the water was to blame.

Ensminger's wife was pregnant at Camp Lejeune in the 1970s. Their daughter, Janey, died in 1985 at age 9. He described taking dark-haired Janey to the hospital instead of her third-grade classroom, weeping as he watched her slip away. She told him to stop, that she loved him. She lapsed into a coma. She died that day.

"My question is how many more of these scenarios played out in private hospital rooms or in private rooms of people's homes?" Ensminger asked.

PCE and TCE are believed to be carcinogens. TCE is a degreaser and PCE is used in dry cleaning. Studies link them to cancers and to kidney, liver and immune disorders, as well as childhood leukemia and neural tube defects.

Two earlier government health reports on Camp Lejeune underestimated how many base houses the contamination may have reached, documents show. The Marines failed to correct the error even when they reviewed the reports before publication. Townsend spotted the mistake and notified them in 2000, the Marine Corps acknowledged.

The Marines updated their Web site but never told federal health investigators, despite repeated urging by a Marine headquarters environmental official.

"It is important to set the record straight," Kelly Dreyer, the official, wrote in an e-mail to the base in 2000. Eventually, in 2003, Townsend and Ensminger notified the health agency, which is now revising one flawed study.

At a health meeting weeks ago in Atlanta, a former Marine air traffic controller, Jeff Byron, accused the military's bureaucracy of hindering progress on health studies.

Byron and his wife, Mary, wondered whether they might have prevented their two daughters' litany of health problems, including an oral cleft birth defect, spinal disorder and a rare condition called aplastic anemia. Then they became convinced the water was at fault.

"When we moved into base housing, we thought we were moving into a safe environment," Byron said.

Former Navy Dr. Mike Gros of Houston also is upset at the pace of the health investigations, which so far have focused on health risks to fetuses.

Gros lived with his family in a tidy two-story house near the Camp Lejeune hospital where he cared for women and babies in the early 1980s. Later, as a civilian physician, he was stunned to learn he suffers from a rare T-cell lymphoma, which his physician blames on exposure to TCE.

Gros's weak immune system now keeps him home. His life revolves around his massive drug regimen. A federal appeals court recently rejected his bid to sue the government for contaminating him.

"They drag it out and by the time you get them all done, everybody would be dead anyway," he said. "That's the whole purpose of their delaying tactics and it's succeeding."